Molecular mechanisms involved in movement disorders such as Parkinson's disease and tardive dyskinesia are investigated in relation to the role of the calcium binding protein, calmodulin, in dopamine receptor altered sensitivity states. Membrane components of the dopamine linked adenylate system involved in altered responsiveness are analyzed in rat brain striatal tissue following chronic administration of haloperidol. These include dopamine sensitive adenylate cyclase activity, calmodulin content, and the coupling of dopamine receptor to adenylate cyclase by guanosine triphosphate.